1. Field of the Invention
The present invention relates to a navigation system for a motor vehicle having a processor for calculating a route between a starting location and a destination, a reader connected to the processor for reading map data from a data medium, means for determining the vehicle position, an input unit connected to the processor and an output unit connected to the processor.
2. Description of the Related Art
Navigation systems for use in motor vehicles are known. The map data required for route calculation is stored on a changeable data medium which generally comprises a CD-ROM. The map data stored on the CD-ROM covers a particular geographical area, which is usually bounded by the borders of a country (in Europe) or a state (in the United States). On journeys beyond the national or state borders, the CD-ROM therefore needs to be changed when the border is crossed, and the CD-ROM for the particular country or state which the motor vehicle is entering needs to be inserted. In addition, the driver then needs to input the new destination, so that the route can be calculated. This procedure is frequently regarded as unsatisfactory.
The object of the present invention is therefore to specify a navigation system which ensures simplified operation, even when leaving the geographical area whose map data is stored on the currently inserted CD-ROM.
The object of the present invention is achieved by a reader designed to hold a plurality of changeable data media and to read data selectively from one of the data media. The object of the present invention is also met by a navigation system containing means for selecting a data medium on the basis of the vehicle position. The navigation system according to the present invention includes a reader into which a plurality of data media may be inserted. When the data media comprise CD-ROMs, the reader comprises a CD changer. A plurality of CD-ROMs may be inserted into the CD changer and data is read from one of these CD-ROMs. The navigation system according to the present invention may additionally include means for selecting a data medium on the basis of the vehicle position. Navigation systems constantly ascertain vehicle position so that the required navigation information is output at the correct time. The vehicle position which is already determined by the navigation system may additionally be used to determine whether the geographical location corresponding to the vehicle position is available on one of the available CD-ROMs and possibly which CD-ROM it is on. This feature enables automatic selection of that CD-ROM which contains the geographical data for the current position.
On journeys in two different countries whose map data is stored on two different CD-ROMs, the starting location and the destination may, for example, be input into the navigation system. In addition, the location of a border crossing as an intermediate destination may also be input. The route is then first planned between the starting location and the intermediate destination using the first CD-ROM which contains the starting location. When the intermediate destination is reached, the first CD-ROM is changed and a route is planned from the intermediate destination to the destination. In this case, the CD changer is controlled by the processor which is running an appropriate computer program.
In an alternative embodiment, the navigation system is designed for route calculation using at least two databases which are stored on different data media. In this alternative embodiment, the driver merely inputs the starting location and the destination. The route is then planned with automatic selection of an intermediate destination.
Under some circumstances, a reader which is able to hold a plurality of data media cannot be arranged in the immediate vicinity of the processor for space reasons. This means that, when the processor is connected to the reader in the motor vehicle, relatively long distances sometimes need to be bridged using cable. In one particular embodiment according to the present invention, the reader and the processor to be connected via a wireless connection such as, for example, by a radio interface.
The navigation information may be output both via an audio output unit and via a visual output unit. The destination, for example, may be input using a keypad. In an optional embodiment, a voice input unit is connected to the processor thereby allowing an input to be made during the journey.
So that alternative routes may also be offered to the driver in the event of traffic obstructions on the originally planned route, the navigation system may be connected to an appliance for receiving traffic information so that traffic information may be taken into account during calculation of a route. Instead of being connected to an appliance, the navigation system may include such an appliance. The appliance for receiving traffic information may, for example, comprise a car radio having a Radio Data System/Traffic Management Channel (RDS/TMC) reception part, so that the traffic information transmitted by the radio stations as background to the program in progress can be received and forwarded directly to the navigation system for further processing. Alternatively, the appliance for receiving traffic information may also include a mobile radio connected to the navigation system. Mobile radio providers also provide traffic information which can be forwarded to the navigation system from the mobile radio for further processing. Particularly in the latter case, a wire-less link between the mobile radio and the navigation appliance is again preferred. More specifically, the mobile radio may be connected to the processor via a short-distance radio link based on the Bluetooth method.
Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. It should be further understood that the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein.